I am trying to repair this laptop that have estrange behaviors.

It start-up as soon as ac adapter is connected, but with no image and seems to hang at the very beginning. (dont tries to boot from hd nor usb)

When in this state, if I push power button for 3 or 4 seconds, it goes to stand by, but immediately goes back to on, and hangs.

With battery only, (without ac adapter) it start to run as soon I push the power button, and goes off and stays in off state when I keep power button down for 3 seconds. (nothing strange here)

Cpu and memory gets a normal temperature, (perhaps a bit hot, but not much) and a bit later, fan start to run.

I have only the boardview, but no schematic.

Anyone knows about a similar schematic, or faced a problem like that?

Thanks in advance for your help.

I forgot to say that this post started in this thread:
viewtopic.php?f=70&t=89694&p=743488#p743488

Hi,
some more information:
I have checked almost all main voltage in the motherboard, and there is one of them that seems to me is out of order.

It is P_VCORE_VGFX_VCC_20 in pin 8 of pu8003, there is 5 volts on it, and seems a bit high.

I have been using only the boardview, so can't see on the schematic.

Could someone check this voltage in a good motherboard?

Thanks in advance.